Stormy conditions continue with localized enhanced snowfall amounts. New storm slabs will build over a complex snowpack increasing the likelihood of triggering large, destructive avalanches over the coming days.
Numerous problematic weak layers exist in the top meter of the snowpack, at prime depths for human triggering. Be especially cautious around steep openings within and near treeline elevations.
New snow and strong westerly wind will likely build new and reactive storm slabs, especially in leeward terrain features that may see more loading from the wind. The new snow may overly lingering wind slabs that formed on the weekend from northeast wind. Dry loose avalanches will likely occur from steeper terrain.
A layer of large and weak facets sits near the base of the snowpack. This layer continues to produce very large avalanches that can travel far. The likelihood of natural and human-triggered avalanches will increase as snow accumulates. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer.
Natural avalanche activity is expected on Wednesday due to new snow combined with blowing ridgetop wind.
On Monday, numerous wind slab and storm slab avalanches were reported up to size 3. These occurred on all aspects at treeline and alpine elevations.
Last weekend, various deep persistent slab avalanches were also triggered naturally, being large to very large (size 2 to 4). The avalanches occurred on all aspects between 2400 and 2800 m.
High-consequence avalanche activity is occurring daily, which is ongoing for several weeks now. Most of the avalanches over the past week released between 1800 and 2800 m, on all aspects. See here for information on a fatal skier-triggered avalanche incident from last week.
Your best defense is to stay diligent in choosing low-consequence terrain away from overhead exposure. Stay disciplined and adjust your expectation this winter. See more on the potential of triggering deeper weak layers Forecasters' Blog.
10-25 cm of new storm snow accompanied by light to moderate westerly wind will likely build reactive storm slabs and wind slabs in lee terrain features. The new snow will overly previously wind-affected snow in the alpine and a small layer of surface hoar crystals in wind-sheltered terrain.
A melt-freeze crust up to 1700 m around Revelstoke and 2000 m further south is buried about 20 to 50 cm deep. At this same depth, a small layer of surface hoar crystals may be found around treeline and lower alpine elevations in wind-sheltered terrain.
Two layers of surface hoar which formed in early January are 50 to 100 cm deep. These weak layers continue to be reactive to human triggering, although snowpack tests are starting to indicate they may be slowly strengthening.
Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region, as described in the Avalanche Summary.
Tuesday Night
Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements expected. Ridgetop winds strong from the West. Treeline temperature -14 °C.
Wednesday
Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements possible. Ridgetop wind strong from the West and treeline temperature -10 °C.
ThursdayCloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible. Ridgetop wind light from the southwest and treeline temperature -10 °C.
FridayCloudy with snowfall, accumulation 5 to 15 cm. Moderate ridgetop wind from the southwest. treeline temperature -5 °C.
More details can be found in the Mountain Weather Forecast.
